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Jan. 12, 2012 -- Have you ever gotten one of those scary chain emails telling you that your deodorant may cause breast cancer? If so, you are not alone. These show up in many people's in-boxes from time to time.

It has to do with certain underarm products that contain preservatives called parabens. These chemicals can act like the hormone estrogen in the body. Estrogen is known to fuel certain breast cancers. Many breast cancers develop in the part of the breast closest to the armpit, where antiperspirants and other underarm products are used.

Now a new study shows that yes, there is evidence of parabens in 99% of breast tissue samples taken from women with breast cancer, but many of these women did not use any underarm products. Most major brands of deodorants and antiperspirants no longer contain parabens.

So where are all the parabens coming from? Parabens such as methylparaben, ethylparaben, propylparaben, butylparaben, isopropylparaben, and isobutylparaben are also found in makeup, moisturizers, and hair care and shaving products.

The new study included 40 women with breast cancer who chose to have a mastectomy. Researchers looked at four samples of breast tissue from each woman. The tissue samples came from several locations within the breast, including the armpit region.

Fully 99% of the tissue samples had evidence of at least one paraben, and 60% showed evidence of five. Paraben levels did not seem to play a role in the cancer’s location or whether or not the cancer was fueled by estrogen.

The findings appear in Journal of Applied Toxicology.

Should You Try Paraben-Free Personal Care Products?

The new study does not prove that personal care products cause breast cancer. But “the fact that parabens were present in so many of the breast tissue samples does justify further investigation,” said Philippa Darbre, PhD, of University of Reading in the U.K., in a news release.

“Although the environmental exposure to parabens as a cause of breast cancer is a possibility, there is no conclusive data thus far to state this as fact,” says Katherine B. Lee, MD, in an email. She is a breast specialist at the Cleveland Clinic Breast Center in Ohio. “The study suggests that if there is a relationship between parabens and breast cancer, it may be a complex one.”

Don’t be scared of your cosmetics, she says. "Further studies need to be performed to determine if there is a relationship between parabens and breast cancer, but if one is concerned, there are natural products without parabens that could be used.”

Marisa Weiss, MD, does not believe in taking chances with breast health. Weiss, the president and founder of Breastcancer.org and director of Breast Radiation Oncology and Breast Health Outreach at Lankenau Medical Center in Wynnewood, Pa., is a breast cancer survivor.

“There are parabens in many personal products that can be taken into the body in different ways and can stay in you,” she says. “Our tissues can be storage lockers for chemical such as parabens.”

“Better safe than sorry,” she says. “Avoid products that contain hormonally active ingredients, including parabens.” Weiss practices what she preaches: “I use things that are good enough to eat.”

Is There a Link Between Parabens and Breast Cancer?

Not so fast, critics of the new study say.

Linda Loretz, PhD, is the director of Safety and Regulatory Toxicology for the Personal Care Products Council, a Washington D.C.-based trade group representing the global cosmetic and personal care products industry. She reviewed the new findings for WebMD. “The paraben levels don’t correlate with tumor location, estrogen, or any attribute of breast cancer, so it is hard to find any real meaning in these findings,” she says.

“This study underscores the folly of trying to blame a specific consumer product for not only exposure to certain chemicals, but for exposure to those chemicals being responsible for causing a specific disease,” says Jeff Stier. He is a senior fellow at the National Center for Public Policy Research, a conservative think tank based in Washington, D.C.

The research actually undermines any link between breast cancer and deodorants, he says.

Dana Mirick, of the Fred Hutchinson Cancer Research Center in Seattle, agrees. Mirick and colleagues published a study in 2002 looking at antiperspirant use and breast cancer risk. “The present study, in which measurable levels of parabens were found in the breast tissue of women regardless of their use of underarm products, seems to be in agreement with our previous results, namely that use of underarm products does not appear to be a significant contributor to the risk of developing breast cancer,” Mirick says in an email.

Sharima Rasanayagam, PhD, is not so sure. She is the director of science for the Breast Cancer Fund, a San Francisco, Calif.-based advocacy group that focuses on environmental links to breast cancer. “This study provides another piece in the puzzle around parabens and their potential link to breast cancer,” she says.

“We know that parabens are estrogen mimickers, and so we continue to be concerned about our exposure to these chemicals through consumer products like cosmetics,” Rasanayagam says in an email.